Experimental and FEM analysis of AFRP strengthened short and long steel tube under axial compression

This paper presents the results of an experimental and numerical study of the behavior of circular hollow section (CHS) steel tubes strengthened by Aramid fiber-reinforced polymer (AFRP). The aramid fiber used for this experiment is available under the trade name of Kevlar 49. In this study, thin-walled circular steel tubes externally bonded with fiber in the hoop direction were tested under axial compression to examine the effects of the AFRP thickness, on their axial load carrying and shortening capacity. The three-dimensional finite element models (FEM) of AFRP strengthened circular hollow section (CHS) was developed using ANSYS Workbench Ver. 19.0 and ACP (ANSYS Composite Prep/Post) tool considering both geometric and material nonlinearities. The effects combined of AFRP damage and interlaminar failures for the bonded interface are modeled within FEM using “Hashin” failure criteria and Cohesive Zone Model (CZM), respectively, to provide an accurate simulation. The results involving the failure modes, load vs. axial shortening curve and ultimate load capacity, were obtained from the experimental and numerical simulation and compared for validation. Both the experimental and numerical results are consistent, demonstrating that AFRP external strengthening can considerably enhance the strength of steel tube columns by 96% for short tubes and 23% for long tubes using 3 mm thickness of AFRP.